If C is creep coefficient, f is original pre-stress in concrete, m is modular ratio, E is Young’s modulus of steel and e is shrinkage strain, the combined effect of creep and shrinkage is________________?
A. (1 – C) mf – eE
B. (C – 1)mf + eE
C. (C – 1)mf – eE
D. (1 – C)mf + eE